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In 2005, poisoning remained the second leading cause of injury death in the United States, after surpassing firearms for the first time in 2004. The vast majority of poisoning deaths are due to unintentional drug overdoses. Narcotic-related deaths have played the largest role in the increase in all poisoning deaths from 1999 to 2005 (the years for which data are available). They accounted for 56 percent of all poisoning deaths in 2005, increasing from 50 percent in 1999. Their absolute numbers increased 84 percent over the 7 years. Methadone-related deaths have increased more than other narcotic-related deaths.

Methadone is a narcotic drug indicated both for the treatment of pain and for the treatment of opioid dependence. The cost of methadone is less than that of other narcotic pain killers. However, with the drug's half-life significantly longer than its effect on pain, the initial proper dosing of methadone is difficult and not all physicians are aware of its varying equivalence to other opioid medications. (Personal communication, Kenneth Hoffman, M.D., M.P.H., Center for Substance Abuse and Treatment, SAMHSA.) Guidelines addressing the complexity of the relationship between different types of opioids, including methadone, have been published by the Department of Defense and Veterans Administration (Management of Post-Operative Pain (POP) accessed 27 Aug 2009).

It has been difficult to determine the extent to which increases in opioid-related deaths have been due to specific prescribing practices, improper taking of the medication by patients, diversion of the drug from the patient to someone else, or other means. In July 2007, a SAMHSA-sponsored conference on methadone mortality concluded that all forms of methadone distribution (tablets, diskettes, and solution) continue to rise, with the greatest rise in distribution coming from tablets distributed through pharmacies; and the circumstances of methadone-associated deaths vary by state, suggesting a complex phenomenon. (Summary Report of the Meeting: Methadone Mortality – A Reassessment [PDF - 425 KB] page 3 accessed 30 Jan 2008).

Of all narcotic drugs mentioned in poisoning deaths, methadone had the largest relative increases. The absolute number of poisoning deaths mentioning methadone was less, however, than the number of deaths mentioning cocaine or other opioids. Other opioids include pain relief drugs such as oxycodone, hydrocodone, and fentanyl (Table 1).

Since 1999, between 73 and 80 percent of poisoning deaths mentioning methadone have been classified as unintentional (3,701 such deaths in 2005), with an additional 11 to 13 percent being of undetermined intent, 5 to 7 percent as suicides, less than 1 percent as homicides, and about 1 percent were injuries other than poisoning. Over this same period, 3 to 6 percent of deaths where methadone was mentioned were not coded as injury deaths (Table 2).

Age

Age-specific rates for methadone death are higher for persons age 35-44 and 45-54 years than for those younger or older. This pattern has been true for all of the 1999-2005 period (Figure 2). Admittedly, the rates are quite low relative to all poisoning deaths, but the patterns are similar in that the rates are high for those in middle-age groups. Among those aged 55-64 years, the rate in 2005 was nine times the rate in 1999; for those in each of the 10-year age groups covering the span 25-54 years, the rates in 2004 were four to six times the rates in 1999. The largest increase was for young persons 15-24 years; the rate in 2005 was 11 times that in 1999. The rate for those 15-24 years, however, was unchanged from 2004 to 2005.

States

Table 3 shows state data for all poisoning deaths that mentioned methadone. State- specific comparisons should be interpreted with caution as many of the state-specific data are based on very small numbers. In 2005, crude state death rates for methadone-related deaths ranged from less than 1 per 100,000 in many of the largest states like California, New York, Texas, and Pennsylvania to 4 to 5 per 100,000 in Maine, Utah, Washington, Nevada, and Kentucky.

About the data

The estimates in this report are from the National Vital Statistics System (1). Poisoning deaths include those resulting from accidental or intentional overdoses of a drug, being given the wrong drug, taking the wrong drug in error, or taking a drug inadvertently. Poisoning deaths also include those associated with solid or liquid biological substances, gases or vapors, or other substances such as pesticides or unspecified chemicals. Deaths can be unintentional, intentional, or of undetermined intent (2). Such deaths can be defined either by their International Classification of Diseases and Related Health Problems (ICD)-10th revision external cause of injury codes or by their ICD-10 diagnosis codes. The external cause codes have two dimensions that indicate the broad categories of substances involved such as drugs and alcohol, and the intentionality of the death, reflecting whether the death was certified as unintentional, a suicide, homicide or legal intervention, or of undetermined intent. The ICD-10 external cause codes used to define poisoning as an underlying cause of death include X40-49, X60-X69, X85-X90, Y10-Y19, Y35.2, or *U01(.6-.7). These are the codes that have been adopted internationally to define poisoning in the external cause of injury matrix for ICD-10.

Poisoning diagnosis codes are used in conjunction with external cause codes to identify the specific substance(s) or agent(s) responsible. A poisoning death can have one or multiple substances listed on the death certificate; the ICD-10 codes range from T36.0-T65.9. Although these codes help to describe a poisoning-related underlying cause, they are not used for underlying cause-of-death coding (3). Rather, the corresponding external cause code will be designated as the underlying cause.

Methadone is classified separately from other opiates and related narcotics in ICD-10, which has been in use in the United States since 1999, but was not classified separately in ICD-9. The ICD-10 code for methadone is T40.3. This drug is listed within the overall category, ICD-10 T40, for "Poisoning by narcotics and psychodysleptics (hallucinogens)." An unquantifiable proportion of the increase in methadone deaths is due to improvements in data collection and processing, particularly between 2001 and 2002.

Tables

Table 1. Number of poisoning deaths in which specific narcotics and psychodysleptics are mentioned: United States, 1999-2005

ICD-10 code

Substance

1999

2000

2001

2002

2003

2004

2005

Percent change 1999-2005

Percent change 2004-2005

All poisoning

19,741

20,230

22,242

26,435

28,700

30,308

32,691

65.6

7.9

T40

Poisoning by narcotics and psychodysleptics, all

9,955

10,173

11,480

14,247

15,731

16,735

18,347

84.3

9.6

T40.1

Heroin

1,964

1,846

1,782

2,091

2,080

1,881

2,011

2.4

6.9

T40.2

Other opioids

2,757

2,932

3,484

4,431

4,877

5,242

5,789

110.0

10.4

T40.3

Methadone

786

988

1,456

2,360

2,974

3,849

4,462

467.7

15.9

T40.4

Other synthetic narcotics

732

784

962

1,301

1,406

1,668

1,744

138.3

4.6

T40.5

Cocaine

3,832

3,565

3,840

4,612

5,212

5,461

6,228

62.5

14.0

T40.6

Other and unspecified narcotics

2,902

2,880

2,881

3,143

3,117

2,761

2,875

-0.9

4.1

T40.7

Cannabis

37

41

37

50

61

99

112

202.7

13.1

NOTES: Substance-specific data are not additive because a death certificate could have multiple drugs listed. ICD is International Classification of Diseases. Poisoning deaths for Opium (ICD-10 T40.0), LSD (ICD-10 T40.8), and Other and unspecified psychodysleptics (ICD-10 T40.9) are not shown separately because there were fewer than 10 deaths in any year.

SOURCE: CDC/NCHS, National Vital Statistics System.

Table 2a. Deaths with mention of methadone for poisoning, other injury and noninjury causes of death and percent change: United States, 1999-2005

1999

2000

2001

2002

2003

2004

2005

Percent change 2004-2005

Percent change 1999-2005

All poisoning deaths

19,741

20,230

22,242

26,435

28,700

30,308

32,691

8

66

All poisoning deaths with mention of methadone

786

988

1,456

2,360

2,974

3,849

4,462

16

468

All deaths (injury and noninjury) with mention of methadone

831

1,060

1,559

2,471

3,117

4,031

4,638

15

458

Unintentional poisoning with mention of methadone

623

778

1,158

1,911

2,452

3,202

3,701

16

494

Suicide by poisoning with mention of methadone

56

72

111

149

146

195

232

19

314

Undetermined intent by poisoning with mention of methadone

105

138

186

295

370

441

523

19

398

Nonpoisoning injury deaths and nonjury deaths both with mention of methadone

45

72

103

111

143

182

176

-3

291

Table 2b. Percent distribution of deaths with mention of methadone for injury and noninjury causes of death: United States, 1999-2005

1999

2000

2001

2002

2003

2004

2005

All deaths (injury and noninjury) with mention of methadone

100.0

100.0

100.0

100.0

100.0

100.0

100.0

Unintentional poisoning with mention of methadone

75.0

73.4

74.3

77.3

78.7

79.4

79.8

Suicide by poisoning with mention of methadone

6.7

6.8

7.1

6.0

4.7

4.8

5.0

Homicide by poisoning with mention of methadone

0.2

0.0

0.1

0.2

0.2

0.3

0.1

Undetermined intent by poisoning with mention of methadone

12.6

13.0

11.9

11.9

11.9

10.9

11.3

Nonpoisoning injury deaths with mention of methadone

0.5

0.9

1.0

0.6

0.6

0.7

0.5

Noninjury deaths with mention of methadone

4.9

5.8

5.6

3.8

4.0

3.8

3.3

Note: Homicide by poisoning with mention of methadone is not shown separately because there were fewer than 10 deaths in any year.

0.0 Quantity more than zero but less than 0.05.

SOURCE: CDC/NCHS, data from the National Vital Statistics System.

Table 3a. Methadone-related poisoning deaths in 1999-2005, ratio of deaths in 2005 to deaths in 1999, and crude death rates for 2005, by state -- Number of methadone-related poisoning deaths1

1999

2000

2001

2002

2003

2004

2005

Ratio 2005:1999 2

Methadone deaths per 100,000 population, 2005

United States total

786

988

1,456

2,360

2,974

3,849

4,462

5.7

1.5

Alabama

16

12

26

33

25

46

47

2.9

1.0

Arizona

20

14

28

57

71

66

87

4.4

1.5

Arkansas

9

3

9

32

36

50

53

5.9

1.9

California

73

51

37

115

144

205

214

2.9

0.6

Colorado

15

16

19

27

30

40

55

3.7

1.2

Florida

34

51

128

218

270

434

430

12.6

2.4

Georgia

14

16

41

50

71

95

123

8.8

1.3

Illinois

29

56

52

68

64

69

81

2.8

0.6

Indiana

5

5

13

20

45

33

51

10.2

0.8

Kansas

4

5

9

24

22

33

45

11.3

1.6

Kentucky

9

28

50

78

129

129

156

17.3

3.7

Louisiana

4

5

21

41

54

71

102

25.5

2.3

Maine

6

20

13

43

36

55

61

10.2

4.6

Maryland

7

18

20

24

40

96

145

20.7

2.6

Massachusetts

10

8

23

24

36

58

93

9.3

1.4

Michigan

12

14

15

43

50

97

126

10.5

1.2

Minnesota

11

5

12

16

25

33

35

3.2

0.7

Missouri

16

14

19

24

69

41

85

5.3

1.5

Nevada

18

24

47

50

50

86

93

5.2

3.9

New Hampshire

2

7

12

33

37

29

51

25.5

3.9

New Jersey

26

17

27

48

54

50

77

3.0

0.9

New Mexico

32

24

27

32

33

43

28

0.9

1.5

New York

120

94

126

135

147

137

179

1.5

0.9

North Carolina

47

90

107

190

249

267

299

6.4

3.4

Ohio

7

20

37

59

74

141

158

22.6

1.4

Oklahoma

20

38

42

43

92

129

111

5.6

3.1

Oregon

9

28

45

82

88

99

123

13.7

3.4

Pennsylvania

11

18

15

39

73

93

114

10.4

0.9

South Carolina

14

13

15

11

20

40

60

4.3

1.4

Tennessee

12

15

19

44

78

110

134

11.2

2.2

Texas

25

50

89

136

155

160

199

8.0

0.9

Utah

20

27

39

61

80

101

112

5.6

4.5

Virginia

20

37

74

90

112

114

121

6.1

1.6

Washington

52

66

83

140

160

252

269

5.2

4.3

West Virginia3

7

8

38

76

68

106

60

Note 3

3.3

Wisconsin

11

18

21

39

41

72

72

6.5

1.3

Table 3b. Methadone-related poisoning deaths in 1999-2005, by state for states with fewer than 20 deaths in any of the years 2003-2005

1999

2000

2001

2002

2003

2004

2005

Alaska

4

7

0

2

2

4

8

Connecticut

13

15

14

24

19

44

35

Delaware

1

4

4

8

13

8

9

Hawaii

5

3

6

14

7

16

18

Idaho

4

4

10

10

21

23

13

Iowa

2

1

2

8

6

12

21

Mississippi

2

1

5

4

12

5

23

Montana

3

2

3

10

24

21

15

Nebraska

0

2

0

5

0

2

12

North Dakota

0

1

2

2

0

3

1

Rhode Island

3

7

8

16

20

13

25

South Dakota

0

0

1

0

0

4

4

Vermont

1

2

3

5

11

6

16

Wyoming

1

3

0

4

1

3

4

District of Columbia

0

1

0

3

10

5

9

1 Underlying cause of death was selected as all poisoning, regardless of intent; methadone was listed on the death certificate as contributing to the death.

2 Interpret the U.S. ratio as follows: the number of deaths in the U.S. in 2005 was 5.7 times the number in 1999.

3 A significant number of deaths in West Virginia, including methadone deaths, were incorrectly classified in the 2005 final mortality file because they were still pending a final cause of death at the close of the data year. Thus, the downturn shown for West Virginia is not based on the state's final numbers.

NOTE: An unquantifiable proportion of the increase in methadone deaths is due to improvements in data collection and processing, particularly between 2001 and 2002.